"For those who already own the older 600mm lens the decision becomes slightly more clouded. The new lens does not bring any real world sharpness advantages over the older version. The decreased weight and minimum focus distance however may just be worth the cost of the upgrade."

Really??? Pay another 6K just for some weight and closer focus?

He really missed the boat on the reasons to upgrade such as improved image stabilization and all but highly desired increase in AF accuracy with newer bodies like the 5D3 and 1DX due to closed loop AF system....and even with that is it still worth spending 6K to upgrade from the 600 F4L IS? I could buy a couple more 5D3's or a 1DX with that 6K.

"For those who already own the older 600mm lens the decision becomes slightly more clouded. The new lens does not bring any real world sharpness advantages over the older version. The decreased weight and minimum focus distance however may just be worth the cost of the upgrade."

Really??? Pay another 6K just for some weight and closer focus?

He really missed the boat on the reasons to upgrade such as improved image stabilization and all but highly desired increase in AF accuracy with newer bodies like the 5D3 and 1DX due to closed loop AF system....and even with that is it still worth spending 6K to upgrade from the 600 F4L IS? I could buy a couple more 5D3's or a 1DX with that 6K.

I don't think he missed the boat, at all. Sure, on test charts the 600 II is better. But the original was very sharp. The AF might be slightly more accurate with a new body - but the AF on the old superteles was already excellent.

There's no way I'd have considered buying a 600/4 MkI, even if it cost less than a 300 MkI. The original is too heavy to hike with, too heavy to handhold. I'd have bought the 500 I, even though it's really not long enough for me on FF. The reduced weight of the 600 II (as the reviewer aptly stated, it's a 600/4 lens in a 500/4 package) was the main reason I bought the 600 II.

Glenn argues that the 600mm gives 1.44x more magnification than the 500 (i.e. (600/500)^2) not 1.2 (600/500). But, is that relevant? The resolution of a lens, the most important factor, is a linear function of focal length, not of length squared. For example, a 600mm lens will give the same size image as a 500mm at 20% further away, not 44% further. When you use binoculars, you talk about x8 vs x10, i.e. the linear magnification, not x64 vs x100, the square. A 600mm lens would seem to me to be a 20% increase in reach, not 44%.

A subject in the frame is not linear, though...it exists in two dimensions. If you measure the subject from corner to corner, sure, the increase is 20%. But in terms of area, it sits on 44% more pixels. It is the increase of pixels on subject that really matters when jumping to a longer focal length, and the difference in PoT is 44%, not 20%. The reason this matters is the more pixels you can get onto the subject, the better the relationship of fine detail to noise. Noise is always a pixel-level thing...if fine detail and noise are both pixel level things, the noise can be a real problem. However, if you can get more pixels on subject, then fine detail becomes larger than a pixel, and noise quickly becomes a background (non-obvious) factor.

I recently purchased the 600/4 L II myself. I was using the 100-400mm. Aside from the superior optics and reduced weight, which are the most obvious improvements...the 600mm lens gets me a 125% increase in pixels on subject ((600/400)^2, or 2.25x). The point Glenn is making is entirely valid, and his numbers are also entirely correct (although there is a simpler way to calculate it: (longer/shorter)^2). It isn't the sole reason to upgrade or purchase this lens, but it is a good one.

So I know for sure that you didn't buy the 600 just for it's weight...and since you didn't already have a 600 maybe that is justification to break a wad on the MkII....as well as the fact that you cant buy a mkI new anymore. Either way, havning a 600 mk1, I cannot justify paying 6K on upgrading it, even all new features considered. It's not worth 6K more than the Mk1.

"For those who already own the older 600mm lens the decision becomes slightly more clouded. The new lens does not bring any real world sharpness advantages over the older version. The decreased weight and minimum focus distance however may just be worth the cost of the upgrade."

Really??? Pay another 6K just for some weight and closer focus?

He really missed the boat on the reasons to upgrade such as improved image stabilization and all but highly desired increase in AF accuracy with newer bodies like the 5D3 and 1DX due to closed loop AF system....and even with that is it still worth spending 6K to upgrade from the 600 F4L IS? I could buy a couple more 5D3's or a 1DX with that 6K.

I don't think he missed the boat, at all. Sure, on test charts the 600 II is better. But the original was very sharp. The AF might be slightly more accurate with a new body - but the AF on the old superteles was already excellent.

There's no way I'd have considered buying a 600/4 MkI, even if it cost less than a 300 MkI. The original is too heavy to hike with, too heavy to handhold. I'd have bought the 500 I, even though it's really not long enough for me on FF. The reduced weight of the 600 II (as the reviewer aptly stated, it's a 600/4 lens in a 500/4 package) was the main reason I bought the 600 II.

Actually I find the large 600 tele to draw the girls in...so much in fact that I sometimes wish they would leave! (Did I really just say that?)

There is no doubt that owning one you have to be prepared in advance to answer a lot of questions and/or ignore the ones with obnoxious comments about how many months rent they could pay for the cost of one.

I think the notion that you can get any 600/4 MkI for $6000 is misguided. You can find them for that cheap...but when you look at the condition of the versions that people are selling for that low of a price, they are NOT in the greatest of condition. Nicks, scratches, enamel discoloration, missing or broken accessories, etc. I was just in the market for these lenses, and I searched every store online, including eBay and Craigs List, before finally buying a brand new EF 600 f/4 L II from Vistek in Canada (the USD price was $10,865, plus $67 shipping and a 1.5% currency exchange fee...couldn't freaking pass that deal up!!)

In my searches, however, I found that an EF 600mm f/4 L Mark I lens, in good condition, with all accessories in good, working condition, including the hard case, was closer to $9000 than $6000, and in a couple instances where the whole kit was in perfect condition, not even a nick in the enamel, AS SOLD prices on eBay were ~$9800. Assuming the condition and completeness of the kit matters to you, the difference between an old Mark I and a new Mark II is not $6000. That would be the difference between a brand spankin new, list price Mark II and a fairly beat up Mark I. The difference between a sale price Mark II and a great condition Mark II is maybe $2000 to $2500.

In that respect, if you own a Mark I, and you've kept it in good condition, have all the accessories and the hard case...your "upgrade price" is likely to be far less than $6000, possibly as little as $2000. For that price, the reduction in weight, better AF, double the IS capability, superior IQ, and a warranty (!!)...well, it's well worth it!

Glenn argues that the 600mm gives 1.44x more magnification than the 500 (i.e. (600/500)^2) not 1.2 (600/500). But, is that relevant? The resolution of a lens, the most important factor, is a linear function of focal length, not of length squared. For example, a 600mm lens will give the same size image as a 500mm at 20% further away, not 44% further. When you use binoculars, you talk about x8 vs x10, i.e. the linear magnification, not x64 vs x100, the square. A 600mm lens would seem to me to be a 20% increase in reach, not 44%.

But isn't he talking about an increase in pixels on the subject, not reach? I'm not doing the math here (nor will I... nor do I really care) but the point he's trying to make is that the lowered minimum focus distance allows a drastic increase in the maximum magnification of the objects shot. Helps when you have to crop down/print etc.

I disgree. I got 600 mk1 from Adorama that was D rated for 6000.00. Not a scratch or spec of dust. Keys strap and manual were still in the original package. The lens was flawless. Plus it came with their standard 30 days return policy. Not misguided at all if you buy from a reputable company.

I think the notion that you can get any 600/4 MkI for $6000 is misguided. You can find them for that cheap...but when you look at the condition of the versions that people are selling for that low of a price, they are NOT in the greatest of condition. Nicks, scratches, enamel discoloration, missing or broken accessories, etc. I was just in the market for these lenses, and I searched every store online, including eBay and Craigs List, before finally buying a brand new EF 600 f/4 L II from Vistek in Canada (the USD price was $10,865, plus $67 shipping and a 1.5% currency exchange fee...couldn't freaking pass that deal up!!)

In my searches, however, I found that an EF 600mm f/4 L Mark I lens, in good condition, with all accessories in good, working condition, including the hard case, was closer to $9000 than $6000, and in a couple instances where the whole kit was in perfect condition, not even a nick in the enamel, AS SOLD prices on eBay were ~$9800. Assuming the condition and completeness of the kit matters to you, the difference between an old Mark I and a new Mark II is not $6000. That would be the difference between a brand spankin new, list price Mark II and a fairly beat up Mark I. The difference between a sale price Mark II and a great condition Mark II is maybe $2000 to $2500.

In that respect, if you own a Mark I, and you've kept it in good condition, have all the accessories and the hard case...your "upgrade price" is likely to be far less than $6000, possibly as little as $2000. For that price, the reduction in weight, better AF, double the IS capability, superior IQ, and a warranty (!!)...well, it's well worth it!

Initially, I had some problems with my lens. It was mis-calibrated at the factory. Now it's producing the images it should have in the first place. Here are a few non-bird images taken this year. The last was taken with the Canon 135mm f/2.0L just for some perspective. The fireworks were taken from 5 miles away on Emigrant Hill overlooking the Wildhorse Casino near Pendleton, Oregon.